Means for expanding hollow bodies



- July 27, 1937. w. CAMBEIS MEANS FOR EXPANDING HOLLOW BODIES Filed 'Feb. 17, 1954 I 2 Sheets-Sheet l Arr'oRA/Ey July 27, 1937. w. CAMBEIS 2,083,131

MEANS FOR EXPANDING HOLLOW BODIES Filed Feb. 17', 1954 2 Sheets-Shem 2 Fig. 6.

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Patented July 27,. 1937 UNITED STATES PATENT OFFICE Walter. Cambeis, Kassel, Germany Application February 17, 1934, Serial No. 711,683

In Germany February 20, 1933 10 Claims. ((51. 153-79) The presentinvention relates to means for expanding hollow bodies, more particularly the stay bolts of the fire boxes of locomotives, or for im- .hammer or percussive'tool, it is well-known to drive one or more mandrels into corresponding cavities of a hollow body or a not previously prepared material. At the end of the driving operation the mandrel must be removed from the cavity by means of a separate tool. Attempts have been made to loosen the mandrel after each stroke of the driving hammer, for instance by causing a spring tensioned during the expanding operation to act upon a counter surface of the mandrel.

The object of this arrangement was to prevent the mandrel from becoming too tightly jammed in the cavity and also to prevent the hollow body from becoming excessively elongated during the driving operation.

This known method has the following disadvantages: Firstly, a separate lining member must be interposed between the mandrel and the hammer used for driving in the mandrel, and secondly, vibrations caused by the continuously changing tensioning and de-tensioning of the spring, are transmitted upon the operator manipulating the hammer, said vibrations imposing an almost intolerable strain upon the operator. Moreover, a considerable amount of power is consumed by the interposition. of the lining member, so that the loosening of the mandrel does not take place in a reliable and perfect manner.

According to the invention, loosening of the mandrel or like member isattained without the use of a tension spring, by theemployment of a muff or sleeve which engages the mandrel and is firmly connected with the hammer or percussive tool. The driving piston or striker of the hammer transmits upon its return to therear dead centre its energy of motion to an impact receiving plate and through the latter and the casing of the hammer to the muif or sleeve and to the mandrel engaged by the muff or sleeve. Any normal pressure air operated hammer with single control action can be utilized for carrying out the in vention, it only being necessary for the purpose of adapting the hammer or percussive tool to provide the hammer casing at the rear end at the cylinder with an impact receiving plate and to provide at the front end of the hammer amuif or sleeve adapted to engage'the mandrel, said mud" or sleeve being for instance in the form a screw capscrewed upon the front end of the hammer casing. The impact receiving plate is securely fixed between the cover of the casing containing the grip or handle, and the casing proper. The muff serving for loosening the mandrel or core is provided with an interior recess within which a 001- lar of the mandrel or like member can move longitudinally by a limited amount.

After the mandrel or like member has been completely driven into the cavity of the hollow body to be expanded or into an unprepared material, the hammer together with the mufi fixed thereto is drawn back until the muff bears upon the collar of the mandrel. During further strik- 'ing' operations of the 'hammer, the forward blow of the piston or striker of the hammer is reduced or entirely cancelled by the increase of the air buffer between the mandrel and the striker. During the return movement of the striker or piston in the casing of the hammer, the striker or piston transmits its energy of motion to the impact receiving plate fixed in the hammer casing and to the muil fixedly connectedwith the casing, the result being that the mandrel is rapidly withdrawn entirely from the cavity.

In order to increase the number of blows or the 3 force exerted by the hammer during the loosening or withdrawing operation, it is advisable to provide in addition to the normal control already provided at the rear dead centre of the cylinder, a further control associated with the main air admission. This additional control serves for supplying an additional regulable amount of pressure air to the space in front of the piston or striker of the hammer or to the space in front of the collar of the mandrel within therecess of 0 the muff, and is so associated or coupled with the normal control member that the additional air supply is opened only after the main supply has been fully opened. The two associated or coupled control members may be operated by a single operating lever or like member, and the times at which the various air conduits are opened are preferably indicated upon the exterior of the hammer.

'The mufi or sleeve engaging the mandrel may be connected in a manner known per se either by a bayonet joint or by screws with the front end portion of the hammer casing and it may be provided with a turnable hand grip. This hand grip facilitates the holding of the hammer in in the rear end of the required correct axial position and it also facilitates the pulling back of the hammer before the final removal of the mandrel from the hollow body or other material.

Another feature of the invention consists in providing the mandrel or hammer actuated by the percussive tool at the rear end of the driving surface which penetrates into the hollow body or other material, with a rearwardly flaring conical surface, the angle of which is steeper than the angle of the forward driving or penetrating surface of the mandrel. tates the loosening or withdrawal of the mandrel after the completion of the expanding operation, particularly in cases in which the cavity of the body to, be expanded is very long or in cases in which the body to be expanded is of considerable strength. By the driving in of the steeper conical portion of the mandrel, the whole bore of the body to be expanded is temporarily and elastically expanded and consequently the mandrel can be,easily released or removed from the hollow body ormaterial acted upon by the mandrel. It is not essential that the steeper conical portion of the mandrel be an exact cone, but it is essential that the inclination of that additional portion should correspond at least to the angle of friction obtaining between the mandrel and the hollow body or other material expanded by the mandrel.

The accompanying drawings show by way of example an apparatus suitable for carrying out the improved method.

Fig. 1 is an axial section through a pneumatic hammer, the handle portion of the hammer being partly broken off,

Fig. 2 is an elevation partly in section of a pneumatic hammer,

Figs. 3 to 5 show in section the front portion of the pneumatic hammer and. a portion of an expandible stay bolt acted upon by the hammer in three different stages of the operation.

Fig. 6 shows a pneumatic hammer according to the invention provided with an additional air control.

Fig. 7 shows a modified construction of the additional air control.

Fig. 8 is a detail section through the front end of the pneumatic hammer showing a hand grip turnable about the axis of the hammer and Fig. 9 shows in elevation an improved construction of the mandrel.

In all the figures I indicates a pneumatic hammer more particularly the casing of the hammer, 2 designates an impact receiving plate fixed the bore of the hammer, 3 is a muff or sleeve fixed at the front end of the hammer and provided'with an internal recess 4. 5 indicates a mandrel or core to be driven into a tubular body or other mate .i to be expanded, and 6 indicates the piston or striker which is reciprocated within the hammer.

In the construction shown in Fig. 1, the striker 6 is provided at its rear end with a reduced portion 6' which co-operates with the impact receiving plate 2. In the construction according to Fig. 2, the striker 6 has no reduced rear portion, but the impact receiving plate 2 has a reduced portion 2" co-operating with the striker.

In the stage of the operation illustrated by Fig. 3 the mandrel 5 has been already driven into a stay bolt 8 of a locomotive by an amount :2. In the stage illustrated by Fig. 4, the mandrel 5 has been further driven into the bolt ,8 by the striker 5 by a further amountw in the direction This arrangement facili- .duits l0, l4, l1, it. sure air control valve for supplying the working of the arrow, the collar 9 of the mandrel reaching in this position a front shoulder of the recessed portion 4. By the reaction of the blow the hammer itself has moved by an amount 1! backwards, that is, in a direction opposite to the direction of the movement of the mandrel 5. In the last stage illustrated in Fig. 5, the mandrel 5 hasv been withdrawn in the direction of the arrow by an amount a which is shown to a somewhat exaggerated scale, and has thereby been loosened within the stay bolt 8.

In Fig. 6, H indicates a control lever for controlling, for instance, the pressure air supply of the hammer. l2, I2 and I2" are control members for controlling the pressure air supply coni5 indicates the usual presmedium through conduits It to the space in front of the piston or striker 6. i9 and 20 indicate springs for returning the control members, l2

etc. to their rest positions, whilst A and B indicate the angles through which the control lever II is turned or depressed for obtaining normal or additional pressure air supply.

The mode of operation of the tool is as follows:

The admission of the pressure air which moves the striker 6 up and down, is effected in known manner, via conduit l0 arranged on the hammer hand grip 9, which'leads to the control member [2 actuated by means of the lever l l. From the control member the pressure air passes through conduit H to an air reversing gear l5 (only diagrammatically indicated) of known kind, from which the air passes according to the position of the gear, either into the space under the impact plate 2 behind the striker 6 or through conduit l6 into 'the space in front of the mandrel 5 and behind the striker 6. The valve gear is known per se and does not form part of the invention. The control device I! which is shown in Fig. 6 in fully closing position, is so constructed that during the first part of its opening'movement, only normal pressure air supply is opened, whilst during the second part of this movement the conduit for the supply of additional fresh air is opened. By turning the lever ll through the angle A, the pressure air supply I0 is first connected via recesses l2 of the control device l2 with the conduit l4; during further movement of the lever ll through the angle B the connection between conduit I0 and conduit I4 is maintained and an additional connection'between a branch 11 of the conduit l0 and a conduit I8 is produced through a second .recess I2 01' the control device l2. The conduit l8 opens into the space between the striker G and mandrel 5 in the proximity of the socket I and represents the path of the additional pressure air which may be admitted in front of the striker 5 either when it is desired to withdraw the mandrel from the workpiece (stay bolt), the mandrel 5 then assuming,

relatively to the hammer casing I, the position shown in Fig. 6, or when it is desired to increase the number of blows of the striker 5 and the driving energy of the tool. By the employment of two springs l9 and 20 of which the spring 20 responds only on opening up the supply of additional pressure air, the operator manipulating the pneumatic hammer receives an indication upon depressing the lever II that the first part of the control operation, that is, the opening of the normal pressure air supply, is completed and that following thereon the additional fresh air supply is being opened.

Fig. 7 shows a somewhat modified valve control which is again operated in a similar manner, that is, on compressing the lever I I through the angle A, a valve 2| forced by a spring 22 upon its seat, isfirst raised and a connection is established between the conduits l0 and I 4. During further depression of the lever II through'angle B, the'second valve 23 loaded by spring 24 is lifted from its seat by means of a projection 2| of the valve 2i, and the additional pressure air path to the conduit l8 from the conduit II) is opened, as the conduit 3 is connected to the space 25 behind the valve 2|.

It is obvious that the means for supplying additional pressure air can be easily applied to old pressure air hammers, particularly if the conduit I8 is constructed as an external hose conduit. With new hammers, the conduit is preferably either completely or partly arranged in the hammer casing l and the hand grip 9.

In Fig. 8, 21 indicates a hand grip which is l rotatably mounted in a-groove 28 of the muff 3 and can be fixed screws 26. v v

In Fig. 9 is shown a mandrel having a normal driving or expanding surface ab which may be cylindrical, conical or parabola shaped: Adjacent to this normal driving or expanding surface there is provided a steeper surface b-c.

As previously stated, the described tool may be used not only for expanding the stay bolts, but may also be used for working boring, breaking and like hammers.

It may be pointed out that applicable to the driving in of 'boring hammers and drilling tools. In this application of the in position by means of invention, the material acted upon is unprepared,

that is, it does not consist of a metallic hollow body to'be expanded, the workpiece acted upon by the pneumatic hammer being rock or other material to be drilled. The striker acts, in these cases, directly upon a hammer or drilling tool. The hammer or drilling tool is after each blow slightly loosened in the r'naterialto be drilled.

I claim:

1..In a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire boxes of locomotives, of the type in which the admission of pressure air to the striker is controlled by a single automatic slide valve located at the top of the hammer casing and actuated by the striker,

the sub-combination ofz'a hammer casing; a mandrellocated in the front end ofsaid casing and provided with a collar; a muff fixedly connected to the front end of the hammer casing engaging said mandrel and having a recess within/whichsaid mandrel has a limited longitudinal movement; a striker adapted to reciprocate in said cylinder casing and. to act upon the mandrel; means for admitting pressure air to the striker; a single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker and an impact plate fixed 'at the rear dead centre of the casing adapted to co-operate with the striker. at the end of the return stroke of the latter, substantially as described.

2. In a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire boxes of locomotives, of the type in. which the admission of pressure air to the striker is controlled by a single automatic slide valve located at the top of the hammer casing and actuated by the striker, the sub-combination of: a hammer casing; a mandrel located in the front end of said casing and provided with a collar; a muff fixedly conthe invention nected tothe front end of the hammer casing. engaging said mandrel and having a recess within which said mandrel has a limited longitudinal movement; a striker adapted to reciprocate in said cylinder casing and to act upon the mandrel;

' means for admitting pressure air to the striker; a single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker; an impact plate fixed at the rear dead centre of the casing adapt ed to co-operate with the striker at the end of the return stroke of the latter; a main pressure j tially as described.

3. In a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire, boxes of locomotives, of the type in which the admission of pressure air to the striker is controlled by .a single automatic slide valve located at the top of the hammer casing and actuated by the striker, the sub-combination of: a hammer casing; a mandrel located in the front end of said casing and provided with a collar; a muif fixedly connected to the front end of the hammer casing engaging said mandrel and having a recess within which said mandrel 'has a limited longitudinal movement; a striker adapted to reciprocate in means for admitting pressure air to the striker; a. single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker; an impact platefixed at the rear dead centre of the casing adapted to co-operate with the striker at the end of the return stroke of the latter; a main pressure medium supply control; an additional pressure medium supply control associated with said main pressure medium supply control, so as to comeinto action only after the main pressure medium supply has 'been fully opened; and a pressure medium supply conduit controlled by said additional control, said conduit opening in front of the striker, substantially as described.

.4. In a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire boxes of locomotives, of the type in which the admission of pressure air to the striker is controlled by a single automatic slide valve located at the top of the hammer casing and actuated by the striker, the sub-combination of: a hammer casing; -a

mandrel located in the front end of said casing and provided with a collar; a. mufi fixedly com said cylinder casing and to act upon the mandrel; I

nected .to the front end of the hammer casing engaging said mandrel and having a recess within which said mandrel has a limited longitudinal movement; a striker adapted to reciprocate in said hammer casing'andto act upon the mandrel;

means for admitting pressure air to the striker; a single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker; an impact plate fixed at the rear dead centre of the casing adapted to cooperate with the striker at the end of the return stroke of the latter; a main pnessure medium supply control; an additional pressure medium supply control associated with said main pressure medium supply control, so as to come into action only after the main pressuremedium supply has been fully opened; and a pressure,

medium supply conduit controlled by said additional control, said conduit opening into the recess of the mufi, substantially as described.

' in which said mandrel has a limited longitudinal movement; a striker adapted to reciprocate in said hammer casing and to act upon the mandrel; means for admitting pressure air to the striker; a single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker; an impact plate fixed at the rear dead centre of the casing adapted to co-operate with the striker at the end of the return stroke of the latter; a main pressure 7 medium supply control; an additional pressure medium supply control associated with said main pressure medium supply control, so as to come into action only after the main pressure medium supply has been fully opened; and a common manually operable member for operating both the main and the additional air control, substantially as described.

6. In a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire boxes I of locomotives, of the type in which the admission of pressure air to the striker is controlled by a single automatic slide valve located at the top of the hammer casing and actuated by the striker,

the sub-combination of: a. hammer casing; a mandrel located in the front end of said casing and provided with a collar; a mufi fixedly connected to the front end of the hammer casing engaging said mandrel and having a recess within which said mandrel has a limited longitudinal movement; a striker adapted to reciprocate in said hammer casing and to act upon the mandrel; means for admitting pressure air to the striker; a single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker; an impact plate fixed at the rear dead centre of the casing adapted to co-operate with the striker at the end of the return stroke of the latter; a main pressure medium supply control; an additional pressure medium supply control associated with said main pressure medium supply control, so as to come into action only after the main pressure medium supply has been fully opened; and a common manually operable member for operating both the *mainand the additional air control, said common manually operable member consisting of an outwardly visible lever. 7 7. In'a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire boxes of locomotives, of the type in which the admission ,of pressure air to the striker is controlled by a single automatic slide valve located at the top of the hammer casing and actuated by the striker, the sub-combination of a hammer casing; a mandrel located in the front end of said casing and provided with a collar; 2. muff fixedly connected to the front end of the hammer casing engaging said mandrel and having a recess within which said mandrel has a limited longitudinal movement; a striker adapted to reciprocate in said cylinder casing and to act upon the mandrel; means for admitting pressure air to the striker; a single automatic slide valve for controlling said means located at the top of the hammer casing mer and for withdrawing the hammer in the longitudinal direction.

8. In a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire boxes of locomotives, of the type in which the admission of pressure air to the striker is controlled by a single automatic slide valve located at the top of the hammer casing and actuated by the striker, the sub-combination of: a hammer casing; a mandrel located in the front end of said casing and provided with a collar; a muff fixedly connected to the front end of the hammer casing engaging said mandrel and having a recess within which said mandrel has a limited longitudinal movement; a. striker adapted to reciprocate in said cylinder casing and to act upon the mandrel; means for admitting pressure air to the striker; a single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker; and an impact plate fixed at the rear dead centre of the casing adapted to co-oprate with the striker at the end of the return stroke of the latter, said mufi being detachably connected to the front end of the easing and being provided with a turnable hand grip, said hand grip being adiustable upon the mufi or upon the hammer casing and fixable in any adjusted position, substantially as described.

9. In a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire boxes of locomotives, of the type in which the admission of pressure air to the striker is controlled by a single automatic slide valve located at the top of a single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker; and an impact plate fixed at the rear dead centre of the casing adapted to co-operate with the striker at the end of the return stroke of the latter, said mandrel having at the end of its normal operative surface an operative surface inclined at a. steeper angle, for the purpose of imparting to the hollow body at the end of the expanding operation a temporary elastic expansion and thereby facilitate withdrawal of the mandrel. I

10. In a pneumatic tool for expanding hollow bodies, more particularly stay bolts of fire boxes of locomotives, of the type in which the admission of pressure air to the striker is controlled by ameans for admitting pressure air to the striker; a single automatic slide valve for controlling said means located at the top of the hammer casing and actuated by the striker and an impact plate fixed at the rear dead centre of the casing adapt" ed to co-operate with the striker at the end of the return stroke of the latter, said mandrel'having at the end of its normal operative surface an operative surface inclined at a steeper angle, for

the purpose at imparting to the hollow body at the end of the expanding operation a temporary elastic expansionand thereby tacilitatlng withdrawal of the mandrel, the angle of said addi e tional operative surface of the mandrel being at least equal to the angle of friction obtaining between the mandrel and the body to be expanded, substantially as described.

'- WAL'EER CAMBEIS. 

